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Absolute Frequency Shifts of Iodine-Stabilized Laser Etalons in Relation to Iodine Purity in Absorption Cells

Author(s): Jan Hrabina, Petr Jedli?ka, Ond?ej ?íp, Josef Lazar
Affiliation(s): Institute of Scientific Instruments, AS CR, Brno

Topic: 2. Development of Optical Measurement Systems
Presentation: Oral

With the optical frequency synthesis based on femtosecond laser technology the use of iodine-stabilized Nd:YAG laser as an optical frequency reference appeared as a one step toward optical clock making possible the transfer of stable optical frequency into radiofrequency domain. We present results of measurement of purity of a set of iodine cells for laser stabilization made at our institute. The purity was tested by improved method based on measurement of induced fluorescence and evaluation by the Stern-Volmer formula. This method was improved by innovation of the fluorescence detection system by introducing compensation for the pumping laser spectral and power instabilities. Further the absolute frequencies of selected iodine hyperfine transitions were measured in direct laser frequency comparison performed with a set of iodine-stabilized Nd:YAG laser etalons with the reproducibility well below the kHz level. The results indicating the iodine cell purity are presented with relation to the absolute frequency shifts. This highlights the influence of iodine cell quality onto the stability and absolute frequency of lasers etalons and also shows the way towards improvements of the iodine cell manufacturing technology.